1. Field of the Invention
The present invention relates to the field of optical lenses, and more particularly to a four-piece imaging lens module capable of providing wider viewing angle and bigger diaphragm.
2. Description of the Prior Art
At present, digital carriers having a lens module, which has a function of photo-taking or filming, will increase its additional value and will attract young group. Some portable digital carriers such as digital cameras, mobile phones, NB, video players or Webcams are also provided with such lens modules. However, these portable digital carriers are small in size, thus imposing some limitations on the lens module. That is, the length of the lens module is inevitably limited.
Besides, the competitive market also results in the reduction of profit. In order to obtain product differentiation, the digital carriers are further provided with high level lens modules for marketing purposes. Preferably, the lens modules should provide wider viewing angle and bigger diaphragm.
However, the present wide-angle lens modules basically include five pieces of lens, which including a ply-lens. Nevertheless, such five-piece design is in conflict with the appeal of light, thin, short and small market trends. In other words, a lens module having five pieces of lens results in the increase of cost, weight, volume and thickness and cannot meet the consumers' needs.
As such, the present invention is arisen to obviate or at least mitigate the above mentioned disadvantages.